1. Field of the Invention
The present invention relates to an apparatus for forming a sample solution containing particles (hemocytes or cells), such as blood or urine, into a sheathed flow, irradiating the sample solution flow with light, and detecting light from the particles to analyze the particle components. More particularly the invention relates to a particle analyzing apparatus such as a flow cytometer in which a one dimension sensor (for example a line sensor) detecting system is utilized to detect particles flowing through a flow cell and to measure light absorbencies of the particles.
2. Description of the Related Art
Apparatus for analyzing properties of particles traveling in a solution by irradiating them with light are conventionally known, for example a flow cytometer, a cell sorter, or an imaging flow cytometer.
U.S. Pat. No. 4,338,024 describes an image analyzing apparatus for forming a flat sample solution (flat sheathed flow) in a flow cell, and irradiating the solution with strobe light to obtain a still picture of particle components.
Japanese Patent Laid-Open (Kokai) No. HEI 2 (1990)-105041 discloses a particle image analyzing apparatus that uses optical deflection elements to obtain data on each portion of a particle by scanning an optical beam in a direction running crosswise relative to the direction in which particles travel, and detecting light passing through the inside of particles with an array type light detector.
Japanese Patent Laid-Open (Kokai) No. HEI 3 (1991)-29835 discloses an apparatus comprising parallel flat glass plates mounted on an optical axis for rotating the glass plates to shift light and adjust the optical axis. The object of rotating the glass plate is to adjust the optical axis in order to obtain the most favorable optical alignment.
Japanese Patent Laid-Open (Kokai) No. HEI 3 (1991)-150444 discloses a particle analyzing apparatus comprising an acousto-optic element that scans a particle with a laser beam in a horizontal direction (which runs at right angle to the direction of the flow of particles) and an acousto-optic element which moves the laser beam in a vertical direction thereby making it possible to scan one particle a plurality of times. The apparatus also adjusts the scanning rate in the flow direction such that it is slower than the flow rate. Both Japanese Laid-Open Patent No. HEI 2(1990)-105041 and Japanese Laid-Open Patent No. HEI 3(1991)-150444 describe a particle image analyzing apparatus in which light is scanned at a high rate in the horizontal direction, which may result in unstable operation. Further, Japanese Laid-Open No. HEI 3(1991)-150444 discloses that particles are scanned a plurality of times by allowing light to track the travel of particles. As a result, a center of one particle is scanned several times, but other portions of the particle are not scanned at all. Still further, the scan rate in the flow direction is reduced to improve the probability that the laser beam is fired onto the center of the particle.
Conventional flow cytometers are not capable of obtaining morphological data of each particle (such as area and circumferential length thereof). In addition, a very expensive video camera and image processing apparatus with high performance are required for obtaining real time characteristics of each particle by forming a sample into a flat flow, irradiating the sample with strobe light and processing an image of the particle captured with a video camera.
Therefore, the present inventors have invented a particle image analyzing apparatus which determines in real time, morphological data of each particle and a quantity of absorbed light by adding to a conventional flow cytometer, a detecting system based on a one dimension image sensor (line sensor) and a signal processing system, scanning an image of the particles that flow through a flat sheathed flow cell and processing detected signals obtained in the process (U.S. Ser. Nos. 07/937,340 and 08/070,687).